Abstract
Probiotics and postbiotics are distinguished by bacterial viability, a factor that fundamentally influences their interactions with the host. Despite this distinction, how bacterial viability shapes host responses remains unclear because direct comparisons using identical strains are technically challenging. Here, we systematically compared the responses induced by live and heat-treated Lactiplantibacillus plantarum 1149(T) using a microfluidic co-culture system with swine intestinal epithelial cells. Transcriptomics and metabolomics revealed fundamentally distinct epithelial responses depending on bacterial viability. Live L. plantarum induced a hypoxia-associated glycolytic shift and PPARG-related transcriptional responses independently of HIF1A, accompanied by the production of lipid mediators including 12,13-diHOME and 9,10-diHOME. In contrast, heat-treated L. plantarum induced nuclear factor kappa B (NFKB)-associated pro-inflammatory gene expression in a Toll-like receptor 4 gene (TLR4)-dependent manner, likely in response to alterations in bacterial surface components. Our findings demonstrate that bacterial viability influences host epithelial metabolic and immune responses, providing a mechanistic basis for the rational selection of probiotic or postbiotic strategies.